fuel sending unit help

Hi
Well here goes the story. My 4.0, 4x4, auto, short bed had a fuel leak
from the sending unit. So I ordered one from a junkie in ca. he sent
it and it didnt work well. It worked as far as sending fuel to the
engine with no leaks. But! the fuel gauge didnt work. So back on the
phone with the junkie in CA and he was very nice and sent another
sending unit. free and didnt want the old one back.
Now running with the new one and the gauge worked well it said I fill
up the tank and it stayed full until today it started moveing and by
the time it showed me having a half tank my comanche stopped moving!
the question now is could I take the first sending unit that worked
but leaked and showed that the fuel gauge also worked. could I replace
the part that tells you how much fuel you have and the sending unit
that works by sending the fuel? with the one that dosnt leak?
Is this way to much? let me know since I need help up here in the
greenmtns

Wouldn't it be cheaper to just get a new sender unit ?

Yes your correct it would be nicer and alot less of a headache.
But only if I could find a new one I would buy it!
Any ideas?
Jeep says they discontinued making them.

http://www.1aauto.com/1A/FuelSendingUnits/Jeep/Comanche/1AFPU01329/154192


I think this should be able to help you. It says it has sending unit connected.

But before you do anything make sure you have a real good ground, your problem sounds more like a bad ground than a bad sending unit.

Check the grounds first, I could see that being a problem as well. The tank doesn't connect well with the body from an electrical standpoint, lots of plastic covers and undercoating between the tank/body. There should be a wire between the outside of the fuel pump that bolts directly to the frame, make sure its there and in good shape and connected well.

Some fuel level senders have a trim pot, you have to pull the fuel pump, but on the sender there may be a plastic screw you can turn, it will adjust the resistance on the sender and adjust how the gauge reads relatively. Don't know if its there, seen it on other vehicles, don't know for sure on the XJ.